AlOx Barriers for Scalable Semiconductor Memories

 Summary

          We are exploring electron tunneling through aluminum oxide barriers grown by plasma and thermal oxidation of aluminum thin films, with rapid thermal post-annealing of the resulting junctions. Our initial goal was the implementation of specially engineered “crested” barriers for fast, scalable, nonvolatile random-access memories (“NOVORAM”) [1-4], which would combine these two types of AlOx. The initial results for single layers had been very encouraging [5]; however, our attempts to combine the two materials in one barrier have (so far) failed, apparently due to complex interfacial chemistry and/or charge trapping. Nevertheless, we have shown [6] that even single layers of plasma-grown aluminum oxide may enable new floating-gate random-access memories (“FGRAM”) which may combine fast operation (sub-10-ns read/erase time) with high electric field endurance (>1010 read/write cycles before breakdown). In contrast to NOVORAM, FGRAM would need the refresh operation similar to that used in the mainstream DRAM memories; however, in contrast to DRAM, FGRAM is highly scalable (by our estimates, to at least 10 nm), and we expect it to be a commercially viable option at the 32-nm technology node and beyond.

 Publications

 

          1. K. Likharev, "Layered tunnel barriers for nonvolatile memory devices ", Appl. Phys. Lett., vol. 73, pp. 2137-2139, Oct. 1998.

          2. A. Korotkov and K. Likharev, "Resonant Fowler-Nordheim tunneling through layered tunnel barriers and its possible applications", Techn. Digest IEDM'99, pp. 223-226.

          3. A. Korotkov and K. Likharev, "Possible cooling by resonant Fowler-Nordheim emission", Appl. Phys. Lett., vol. 75, pp. 2491-2493, Oct. 1999.

          4. K. Likharev, "NOVORAM: A New Concept for Fast, Bit-Addressable Nonvolatile Memory Based on Crested Barriers", IEEE Circuits and Devices, vol. 16, No. 4, pp. 16-21, July 2000: text and figures.

          5. E. Cimpoiasu et al. "Aluminum Oxide Barriers as Possible Components of Layered Barriers", J. Appl. Phys., vol. 96, No. 2, pp. 1088-1093, July 2004.

          6. X. Liu et al., High-Quality Aluminum-Oxide Tunnel Barriers for Scalable, Floating-Gate Random-Access Memories (FGRAM)", in Proc. ICMTD’07, pp. 235-237.

 

| Back to Nanoelectronic Device Home Page |